PPARGC1A and Huntington disease: Evidence from clinical studies, cell cultures, and HD mouse models (notably R6/2 mice) indicates impaired mitochondrial depolarization, disrupted apoptotic signaling (e.g., cytochrome C release, elevated caspase-3, -8, and -9 levels), and reduced expression of metabolic regulators such as Peroxisome proliferator-activated receptor gamma coactivator 1 alpha (PGC-1α) (Ciammola et al. 2006; Chaturvedi et al. 2009).